The invention relates to a cylindrical head boring tool, for example a forstner-boring tool, a hobby boring tool or the like, with a main cutting edge having a center point and extending essentially diametrically across the entire circular crosssection of the boring head and having shearing surfaces, along with chip channels adjacent the main cutting edge, the chip channels being open through the outer edge and extending obliquely through the boring head, such that each end of the main cutting edge adjoins a preliminary cutting edge which coincides with the periphery of the boring head, for a simple guiding of the boring tool, which preliminary cutting edge reaches to the edge of the respective other chip channel, and which is the essentially cylindrically curved wall of the boring head.
Such cylindrical head boring tools are already known. For example, DE-PS4115030 discloses a cylindrical head boring tool fashioned integrally from solid material, with a shaft-supported boring head which is provided with a central point and two peripheral cutting edges with two generally radially extending main cutting edges. The two main cutting edges are associated with chip channels which are open to the peripheral surface and to the rearward face of the boring head. The base of each chip channel is circularly rounded and extends continuously both to the chip surface of the respective main cutting edge and also to the chip channel side wall lying opposite such chip surface. Further, so-called ring hole cutters are known which include chip channels for conducting chips to the outer wall of the boring head.